A more accurate way to track calorie expenditure

Hi there,

I am trying to lose weight, I have a lot of it to lose…… and like a lot of people I am trying to lose weight and get fit through cycling, because we / I enjoy cycling.

I have been using MyFitnessPal to track my calorie intake and have been using TrainerRoad workouts to ensure I am in a calorie deficit, that is along with training goal to get fitter and faster.

However, if I do an hour sweet spot and spend a lot of time at or around my ftp I’m pretty much spending an hour at max HR zones (4 & 5) and trainer road tells me I’ve burnt say 300kcals. If I go outside and cycle for an hour at HR zones 4&5 then I’ve burnt over 1000kcals.

So what is it, I mean I’m 300lbs which is nearly 50lbs from where I started so things are working but I have a goal of sub 200lbs and accurate calorie measurement is going to play a big part in my journey.

Does anyone have any ideas or advice? I’d love to hear what you think.

Thank you


I’m not a nutritionist but maybe @Dr_Alex_Harrison can chime in with some tips. This article by @Dialed_Health help me dial in my calories. The hardest thing for me was finding an average of daily calorie expenditure (active BMR) before exercise, also with a power meter it’s a great way to track calories burned during exercise. Hope the best for you :metal:

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Who’s telling you you’ve spent 1000kcal by cycling for an hour? You’d have to push a lot of watts for that amount of calories. An hour at 160 watts amounts to ca. 600 kcal. For 1000 kcal I think you need to push 240 watts straight for an hour.


Calorie burn is all about number of watts you’re producing and the time you spend doing it. Basing calorie burn off of heart rate is an estimate with pretty high variability. If you’re using a power meter, that’s probably the best estimate you’ll get outside of a lab.


Are you using a power meter outside?

If not, get one. Its not perfect but an estimate of calories burned based on power data is in non scientific terms, about a million times more accurate than an estimate based on heart rate.

Another tip - In the diet/fitness profile, MyFitnessPal allows you to set a base daily activity level (e.g. Active, sedentary). Ignore the fact you workout every day and pick sedentary assuming you are not working a very physical job. You’ll still get credit for your workouts but it will make the overall daily calorie estimate much more accurate.


I’m using ‘lose it’ which is similar to my fitness pal - but when I looked at Bose lose it seemed more user friendly.

I’ve lost 10kgs in a year whilst bumping up my fitness. I don’t think calorie counting is an exact science - but if you’re using a turbo trainer with a HR monitor and power meter built into your turbo then that’s probably as accurate as you’re going to get.

To burn 1000 calories outside on my mtb Strava / Garmin usually get think thats 1.5-2 hours generally. If I go somewhere really hilly it suggests I get approx 1800 calories on a 2.5-3 hour ride.

I always assume it’s overestimating that and try to keep a bit in deficit on those days.

I’ve marked my lifestyle as sedentary and it comes out with a base 1750 calories per day per-exercise so lose weight - although I’ve plateau’d now at 74/75kgs. To lose more I think I’d need to cut daily calories again and I’m just not up for that.

To note on exercise days I do up my calories otherwise I don’t think my training would go well / I’d get fatigued and run down.


This is a good way to get an estimate of your calorie demands in normal day to day life. A power meter on your bike and/or trainer is the best way to estimate expenditure for your rides. Good luck!


If TR is estimating calorie burn from power (more accurate) and outside is estimating calorie burn from HR / weight (less accurate), then I can understand that difference. Most calorie burn estimates I’ve seen from HR are not very accurate. If you don’t have a power meter for outside I would probably use something close to what TR says for a similar duration / effort level.

My 2c is that calorie input / burn calculations are never going to be precise. Thats okay, don’t throw the baby out with the bath water. MyFitnessPal and similar apps are a great way to learn about what goes into your body (often very different from our perception) and what goes out. On the input side, USDA labels are allowed an error margin of 20%, which is huge. And those labels aren’t 3rd party validated for accuracy in most cases. And on the out you can have some bad estimates based off HR. I’d say, do your best to get reasonable estimates on the in/out and then you need to look at body composition / weight / body measurements and use those to identify if you’re gaining weight or stalled out and identify where the problem areas are. Personally, I was tracking pretty closely and then started adding in calories from walking with my fitbit into my total daily calorie expenditure. When I ate more calorie to compensate I ended up gaining weight, when I should have been stable. I chalked it up to bad calorie estimate from my fitbit and stopped counting walking towards my daily calorie goals.

It sounds like you’ve made great progress. Keep it up, take it slow and take your time. Many of these changes you’re making now to lose the weight need to become lifestyle changes that you continue to keep the weight off. I hope it goes well for you.


This may eventually be true, but is not likely to be critical right now.

I wouldn’t put much stock in estimates of calories burned based on HR and weight. Go off of kJ measured by a power meter (or erg or whatever).

My best advice is to use this phase to solidify making cycling a part of your life, which you protect against what life throws your way (within reason – don’t skip your kid’s school recital because you need to get a workout in).

Good luck; you can do this.


A general rule of thumb for me is 1 hour at 200 watts is approx 700 cals. Trainerroad seems to corroborate that.


If you want a good podcast to listen to about this subject. Listen to the first half of this one:

It awnsers most questions you have about losing weight and how the human body works when it comes to calories in/out.


As a general guideline, assume you are under counting the calories you eat and over counting the calories you are burning.

And, after years of tracking calories, my unscientific conclusion is that for all the inherent errors that enter into the process from basic science to your own inadvertent errors, the two biggest sources of error are #1 - “eyeballing” portion sizes (get a food scale if you don’t have one); followed closely by #2 - relying on HR based estimates of calorie burn. Just between those 2, its really really easy to be off on your daily net calorie count by 500+ calories a day.

Counting calories can work but don’t let the fact that numbers are involved fool you into thinking that there is sufficient precision going on such that you can actually dial in your net calorie count to within a Clif Bar :wink: You need to take the numbers as a guide and figure out what works for you.

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First, major props on getting down 50 pounds.

Second, I wrote a calculator for figuring out appropriate kcal and macros as a cyclist. It’s pricey, but worth it.

Third, I wrote a book for you.

Fourth, I’m done advertising now and have some serious advice for you, but first, please understand my advice comes from the perspective of a PhD in Physiology, and having worked 1:1 with approaching 1400 folks for weight loss, many of whom are endurance athletes. I’m down 35 pounds, myself. Half of it muscle loss intentionally (former bobsledder), but the effects on satiety and weight maintenance, and optimal long-term weight calculations are the same.

I would reconsider your sub-200 lbs goal. Target something over 200 pounds. Having carried more weight over some years means the following:

  1. You have higher bone density. (Your skeleton now weighs more).
  2. You have more muscle mass because of carrying higher body weight loads.
  3. You have more skin than someone who has carried less weight. It will weigh more than your skin had you not been heavier.
  4. You have countless cellular and hormonal changes that may make it a very suboptimal approach to target below 200. Hunger will be substantial for the rest of your life if you go that low. You’ll require borderline disordered eating to maintain that low of a weight.


  1. Do what you love in training. Train like a boss.
  2. Always include some endurance training for fitness.
  3. Always include some lifting.
  4. Track calories or macros while losing weight.
  5. Acknowledge hunger.
  6. Lose weight slower than 2 pounds per week.
  7. Take breaks from weight loss. During those breaks, eat a bit more intuitively but pay special attention to fullness and hunger.
  8. Attempt to avoid tracking kcal or macros after one month of maintaining while tracking.
  9. Target somewhere between 200 and 250 pounds as a long-term goal. Let extreme hunger be your guide as to “where is too low.” Try to figure out where that point is, before you’re there. I’d bet sub-220 is not optimal for you but would need more info to be sure.

My weight loss strategy is a simple two pronged approach:

  1. Establish good eating habits and food choices to break even on most days. One thing I like to do is eat a banana or an apple (convenient, not too juicy/messy) an hour before lunch and dinner, as to avoid overeating later. I also substitute ice cream with greek yogurt, milk with almond milk, etc.

  2. Ride a lot of Z2 and get a fairly substantial caloric deficit on those days. Z2 rides of sufficient length naturally allow you to “skip” lunch, i.e. substitute with on-the-bike fueling/snacking. I usually shoot for 50% of the expenditure, e.g. 2,000 Cals consumed during a 4,000KJ ride.

I avoid daily caloric deficits. Done that before and it’s miserable. The body also adapts to that kind of thing.


Wait, wut? From someone who went down from (around) 300 tot 165, I don’t regocognize this at all. Maybe it has to do with the time it took me but I’m perfectly fine with not being hungry and eating very normally (need around 2100Cal to stay 165).
But it did take me a long time, about 5 years slowly going down from 300 to around 220 and then from 220 down to 165 when I started cycling 4 years ago, 22 of which I lost in the last half year of 2021.

I say if your willing to accept that it’s going to take a long time, sub 200 is a perfectly fine goal. But you do have to be mentally very strong to keep going at a slow, steady weight loss pace.


Hi Craig_G you hit the nail on the head. There is such a variation in What my inbuilt, smart trainer, power meter is telling me and what my Heart Rate Monitor (weight and HR) is telling me. If you take that margin of error (difference) and multiply it by 20% of in-accuracy that can creep into food labelling then it all starts to get a bit confusing, and disheartening. That said I think the time is getting closer to when I might need to get a power meter for my bike. Thanks for taking the time to reply :+1:t2:

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PhydomiR way to go! 300 to 165, looks like I’m following in your footsteps. I’m in it for the long haul, I’m old enough to know there are no short cuts. Thank for the link to the podcast I’ll download that and have a listen.
Many thanks and, well, just thank you it can be done!

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@PhydomiR, Your experience is phenomenal. Congratulations on accomplishing that. And I think your approach is very illuminating and instructive.

For long-term maintenance success, the slower the weight loss and the more phasic, the better. The younger you start the weight loss and the shorter time you carried the highest body weights, the more likely you are to be able to maintain >100-pound losses.

I can’t emphasize enough how extraordinary it is that you’ve done that. It puts you in the something like the 99th percentile of the 99th percentile in terms of weight lost.

I understand I’m 100% a soggy wet rag in saying “don’t target sub-200.” I’m not one for quashing lofty goals, and I always encourage people to aim for the pointy end of the results distribution.

I just would hate to see another person be encouraged to target such a low ending body weight that they end up in either of the following scenarios, both of which are probably 1,000x to 100,000x more common than the “150 pounds lost and kept off for good” scenario.

  1. An initial >100 pound loss, followed by a cycle of lose-gain-lose-gain-lose-gain, drifting ever upward on net, and deeply unhappy at their perceived lack of control and believe that they are just psychologically weaker than their peers who have achieved and maintained larger weight loss numbers. (These are very common reports among folks who have achieved >100 pounds of weight loss).

  2. Getting to roughly the halfway point of their initial weight loss goal, being starving, faltering and struggling to lose more weight, being massively disappointed that they can’t even make it past half way (or insert X% that they’re struggling at), and losing motivation due to their perceived failure, rather than celebrating the huge accomplishment and fitness gains that have come with their already massive weight loss.

@Cpaulo, Word to the wise: let the current weight loss and drops you’re seeing in the scale be motivating. But let the fitness gains also drive motivation. If scale losses stall, celebrate how far you’ve come. Don’t allow yourself to tie up all motivation in the progress on the scale. Stalls in scale movement, especially when substantial, can be incredibly demotivating and disheartening if you’re not focused very long-term as @PhydomiR was. Likewise, if you don’t have other fitness goals you’re working towards. I’m glad you’re training with TrainerRoad. It’s a great tool.


I’ve said before on here, I had expected weight loss using Garmin Calorie “burn”, albeit with a reasonable estimation of max heart rate. If I look in connect, and take “active calories”, it’s usually about where I’d expect based on RPE/ spins with power meter (for example my commute). “Active calories” within a handful where I do have power.*

I’m not going to try and contradict the good Doctor. What worked for me was a gradual loss, and hitting a target and then maintaining, before going again. I went from 120kg+ to a period maintaining at 70kg ish - but it was years of that process, and gradually changing diet through tracking on myfitnesspal.

Lockdown 4 took a bit of a toll, so was up about 10kg on that, and gradually working may back down (77 this morning). I’m being more conservative with my deficit this time, as I’m trying to balance training and racing (and “not diet on the bike”) more this time.

*I found wahoo off the wall, on the same criteria, which would put a hefty dent in a deficit until they introduced calories = work. Various phone apps, even worse. All based off the same weight, height, heart rate data.

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Your hourly calories burned when cycling is roughly average Watts times 3.6.
So 100W average over an hour is 360 Cal, 200W is 720 Cal and for 1000 Cal you need to be doing an average of ~280W.

The differences you are seeing from inside to outside is for sure in the way this all is being estimated. If you would use a consistent power meter inside/outside, you would get the same figures for the same effort.

As you were already able to loose 50 lbs, you should be familiar with the slight sensation of hunger that is involved with loosing weight. That is also a good way to go by: Keep eating the right things, keep exercising and eat as much as needed to maintain that little nagging feeling of hunger that goes away if you don’t think about it.